General Motors just announced a plan that will make its cars into rolling data hot spots, allowing passengers to browse the Web, send and receive email, watch movies, listen to streaming music -- the whole nine yards. Is it worth it, or are there better ways to give you car data access?

The Wall Street Journal reports that GM car owners can pay for a 4G LTE high-speed connection via its OnStar service, using AT&T's high-speed network. Sounds good, but there's a few hitches. First is the pricing. There are several different ways to use it. You can pay $5 a day, which might sound cheap, but that means $150 a month if you pay that way, an outrageously high price. Not only that, but the $5 a day gets you only 200 megabytes of data. That's fine if you're only using it for email and some Web browsing. But for music streaming and watching movies? Not a chance.

You can instead opt for the monthly plan, which goes for $50 a month, and includes 5 GB of data. Obviously, that's a much better deal. If you're planning on using your car as a rolling hot spot regularly, it's clearly the way to go.

But it still might not be the best way to go. You can simply use your existing data plan from a service provider, and use its connection in the car. Most cars now offer Bluetooth connections, so you'll not only get data, but also be able to play music over the car speakers, and so on.

Doing that, of course, means you'll use more data than ever, because you'll be using the plan while you drive as well as in other places. So it could push you over your normal data limits. But generally, it's cheaper to pay for the extra data on your cell phone than to pay your normal cell phone data plan, plus $50 for the GM plan. For example, T-Mobile has an $80 plan that includes unlimited data plus unlimited voice and texting. And T-Mobile has an even better deal --- $50 for unlimited data, voice, and text. That's tough to beat.

Even the higher-priced Verizon allows you to buy extra data on an as-needed basis if you exceed your monthly limit. Prices vary according to your plan, but $15 for an extra 1 GB is common.

So should you go ahead with the GM plan? Likely not. Until the prices come down, it's better to go with an existing carrier.